[meteorite-list] Oakley Idaho Iron Meteorite

From: bernd.pauli at paulinet.de <bernd.pauli_at_meteoritecentral.com>
Date: 21 Mar 2007 18:57:47 UT
Message-ID: <DIIE.000000B8000018A8_at_paulinet.de>

Jeremiah wrote:

I was in the Smithsonian a few weeks ago, looking at their collection. I noticed
a very large iron meteorite from Oakley Idaho, that was found in 1926. Does anyone
know how I can find more details on it? That's very close to where my inlaws live.
Its mostly farm land, and every field, has a large pile of rocks that's been plowed
up. I was thinking it might be fruitful to serch those rock piles for more.


Hello Jeremiah and List,

Here's an excerpt from V.F. Buchwald.

Cheers,

Bernd


BUCHWALD V.F. (1975) Handbook of Iron Meteorites, Volume 3, pp. 932-934, excerpts:

Oakley, Idaho, U.S.A. (42?20' N, 113? 42' W; 2,000 m)
Coarse octahedrite, Og. / Bandwidth 1.40?0.30 mm
Neumann bands / Anomalous, judging from the structure (IIIF)
7.3% Ni, 0.28% P, 7.2 ppm Ga, 1.1 ppm Ge, 5.3 ppm Ir

History

A mass of about 113 kg was found in 1926 - 10 miles northeast of Oakley, Cassia County.
It was lying on the surface of the ground on the west side of Harrison Mountain where it was
discovered by two youngsters cutting cedar posts. The meteorite was acquired by the U.S.
National Museum and was briefly described by Merrill (1927a), who gave three photographs
of the exterior. Revised coordinates and an approximate altitude are given above.

Collections: Washington (111.4 kg main mass), Calcutta (14 g).

Description

The mass is a triangular, domed shield with the average dimensions of 58 x 47 x 10 cm. Along one
edge the mass tapers irregularly to a 1-5 cm thick wedge, while near its opposite end it attains
its maximum thickness of 20 cm. The present weight is 111.4 kg, and as yet nothing has been cut
from it. The finders had, however, broken about 1.5 kg from the thinnest part of the edge, leaving
a 16 x 2 cm hackly fracture, and 420 g of this material went to the U.S. National Museum with the
main mass.
The surface shows three distinct morphologies, each of which is rather well developed ... the convex
side was uppermost. The crown of this top side, about 25 cm in diameter and 10 cm high, is much less
corroded than the skirt of the top side - probably because the crown was the only part that projected
above the ground. The crown is covered with typical, angular ablation regmaglypts, 2-4 cm in diameter
and 0.5-1 cm deep; and these are separated by rather smoothly rounded ridges. In a majority of the
cavities a 0.1-0.4 mm thick fusion crust is preserved, indicating that hardly any material here has
been removed through corrosion.
The remaining part of the top side, which was covered by the soil, is considerably corroded. The fusion
crust has disappeared and the regmaglypts have been severely altered ... Finally, the concave underside
shows boldly carved, large regmaglypts. These are in the shape of shallow bowls, 8-20 cm in diameter
and 1-2 cm deep, ... a 0.5-1 mm thick, warty or striated crust. Oakley resembles Cabin Creek, Hra-
schina and Murnpeowie a great deal in the flight-sculpturing ... Oakley ... a coarse octahedrite with
straight, long kamacite lamellae with a width of 1.40?0.30 mm ... The kamacite shows numerous sub-
boundaries decorated with ... phosphides, and Neumann bands are also present.
Taenite and plessite cover about 15% by area ... Schreibersite is present ... as rim zones around troilite.
It is monocrystalline but brecciated. A small of ... rhabdites. Troilite occurs as irregular nodules ...
Daubreelite is present ... The fusion crust is 1 mm thick and composed of layers of metallic melts ...
Under the fusion crust there is a 2 mm thick alpha2 zone ...
Oakley appears to be an anomalous meteorite ...
 
Specimens in the U.S. National Museum in Washington:

111.4 kg main mass (no. 780, 58 x 47 x 10 cm)
15 g fragment, broken from the edge.

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Received on Wed 21 Mar 2007 02:57:47 PM PDT